Question

I have a query that returns’s, amongst other things, the following

I need something that will create a new column that will return 1 if level 1 is null, 2 if level 2 is null and 3 if level 3 is null (there coould be up to 5 levels)

I have no idea where to start with this one so any help would be greatly appreciated.

Answer 1

You should use Case when to decide the new column value.

Please see the following sample pl/sql code which will achieve what you want.

  create table test_level( level1 varchar2(20), 
level2 varchar2(20),
level3 varchar2(20),
level4 varchar2(20),
level5 varchar2(20));

    insert into test_level values(null, 'X', 'X', 'X', 'X');
    insert into test_level values('X', null, 'X', 'X', 'X');
    insert into test_level values('X', 'X', null, 'X', 'X');
    insert into test_level values( 'X', 'X', 'X', null,'X');
    insert into test_level values('X', 'X', 'X', 'X', null);


select * from test_level;

Now use the below query to achieve the new column value.

select level1, level2, level3, level4, level5,      
     (case 
         when level1 is  null then 1
         when level2 is  null then 2
         when level3 is  null then 3
         when level4 is  null then 4
         when level5 is  null then 5
      end) new_lvel
from test_level;